crawler4j

crawler4j is an open source web crawler for Java which provides a simple interface for crawling the Web. Using it, you can setup a multi-threaded web crawler in few minutes. You need to create a crawler class that extends WebCrawler. This class decides which URLs should be crawled and handles the downloaded page. shouldVisit function decides whether the given URL should be crawled or not. In the above example, this example is not allowing .css, .js and media files and only allows pages within ics domain. visit function is called after the content of a URL is downloaded successfully. You can easily get the url, text, links, html, and unique id of the downloaded page. You should also implement a controller class which specifies the seeds of the crawl, the folder in which intermediate crawl data should be stored and the number of concurrent threads.